let obj = {
  age: 18,
  name: "yz"
}
for(let key in obj) {
  console.log(key);
  let value = obj[key];
  Object.defineProperty(obj, key, {
    get() {
      return value;
    },
    set(val) {
      value = val;
      // console.log(value, typeof(obj[key]));
    }
  });
};


obj.age = 123;
console.log(obj)
